Yeah that seems rather good.
Why is it only 40Gb though? Though thats not bad really, I mean I'm using a 120gb drive now, but partitioned so I have 40gb. Its lasting me
but the price is rather high, but again, it uses 10,000RPm's and has a fast access time so you will notice improvements in loading programs and games.
As for setting up a RAID, this isn't a bad option either, though I woulnd't set up a RAID with a drive thats slower than that one. You won't get the performance boost, so yeah, best to get two if you'd do that.